Light emitting device

ABSTRACT

Each of a plurality of light emitting elements has a polygonal shape with five or more corners. An interior angle at each of the corners is less than 180°. The plurality of light emitting elements include a first light emitting element having a first bottom surface, a first top surface opposite to the first bottom surface, and a first lateral side surface between the first bottom surface and the first top surface. The second light emitting element has a second bottom surface, a second top surface opposite to the second bottom surface, and a second lateral side surface between the second bottom surface and the second top surface. The second lateral side surface is provided not to oppose to the first lateral side surface in substantially parallel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U. S. C. §119 toJapanese Patent Application No. 2015-026146, filed Feb. 13, 2015. Thecontents of this application are incorporated herein by reference intheir entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a light emitting device.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2009-267423 andJapanese Unexamined Patent Application Publication No. 2011-109143disclose a light emitting device in which a plurality of light emittingelements each being quadrangular in a plan view are disposed in rows andcolumns.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a light emittingdevice includes a package, and a plurality of light emitting elements.The package has an upper surface and a direction substantiallyperpendicular to the upper surface. The plurality of light emittingelements are disposed on the upper surface. Each of the plurality oflight emitting elements has a polygonal shape with five or more cornersviewed in the direction. An interior angle at each of the corners isless than 180°. The plurality of light emitting elements include a firstlight emitting element and a second light emitting element. The firstlight emitting element has a first bottom surface, a first top surfaceopposite to the first bottom surface in the direction, and a firstlateral side surface between the first bottom surface and the first topsurface. The first light emitting element is disposed on the uppersurface of the package at the first bottom surface. The second lightemitting element has a second bottom surface, a second top surfaceopposite to the second bottom surface in the direction, and a secondlateral side surface between the second bottom surface and the secondtop surface. The second light emitting element is disposed on the uppersurface of the package at the second bottom surface. The second lateralside surface is provided not to oppose to the first lateral side surfacein substantially parallel.

According to another aspect of the present invention, a light emittingdevice includes a package and a plurality of light emitting elements.The package has a recess with a bottom surface and a directionsubstantially perpendicular to the bottom surface. The plurality oflight emitting elements are disposed on the bottom surface. Each of theplurality of light emitting elements has a polygonal shape with five ormore corners viewed in the direction. An interior angle at each of thecorners is less than 180 degrees.

According to further aspect of the present invention, a light emittingdevice includes a package and a plurality of light emitting elements.The package has an upper surface and a direction substantiallyperpendicular to the upper surface. The plurality of light emittingelements are disposed on the upper surface. Each of the plurality oflight emitting elements has a polygonal shape with five or more cornersviewed in the direction. An interior angle at each of the corners isless than 180. The plurality of light emitting elements include a firstlight emitting element and a second light emitting element which areprovided such that one corner of the first light emitting element isclosest to the second light emitting element.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1A is a schematic perspective view showing a configuration of alight emitting device according to a first embodiment;

FIG. 1B is a schematic plan view showing the configuration of the lightemitting device according to the first embodiment;

FIG. 1C is a schematic cross-sectional view showing the configuration ofthe light emitting device according to the first embodiment, taken alongline IC-IC in FIG. 1B;

FIG. 1D is a schematic cross-sectional view showing the configuration ofthe light emitting device according to the first embodiment, taken alongline ID-ID in FIG. 1B,

FIG. 2A is a schematic plan view showing the configuration of a lightemitting element in the light emitting device according to the firstembodiment;

FIG. 2B is a schematic cross-sectional view showing the configuration ofthe light emitting element in the light emitting device according to thefirst embodiment, taken along line IIB-IIB in FIG. 2A;

FIG. 3A is a schematic plan view showing the configuration of a lightemitting device according to Reference Example;

FIG. 3B is a schematic plan view showing the configuration of a lightemitting device according to Reference Example;

FIG. 4A is a schematic plan view showing the configuration of a lightemitting device according to Experimental Example;

FIG. 4B is a schematic plan view showing the configuration of a lightemitting device according to Experimental Example;

FIG. 4C is a schematic plan view showing the configuration of a lightemitting device according to Comparative Example;

FIG. 5A is a flowchart showing an example of a procedure of a method ofmanufacturing the light emitting device according to the firstembodiment;

FIG. 5B is a flowchart showing details of a light emitting elementdisposing operation in the method of manufacturing the light emittingdevice according to the first embodiment;

FIG. 6A is a schematic plan view showing boundary lines virtuallypartitioning a wafer in a light emitting element preparing operation inthe method of manufacturing the light emitting device according to thefirst embodiment;

FIG. 6B is a schematic plan view showing the state where light emittingelements are formed on the wafer in the light emitting element preparingoperation in the method of manufacturing the light emitting deviceaccording to the first embodiment;

FIG. 7A is a schematic cross-sectional view showing a light emittingelement joining operation being a subordinate operation in the lightemitting element disposing operation in the method of manufacturing thelight emitting device according to the first embodiment;

FIG. 7B is a schematic cross-sectional view showing a wiring operationbeing a subordinate operation in the light emitting element disposingoperation in the method of manufacturing the light emitting deviceaccording to the first embodiment;

FIG. 7C is a schematic cross-sectional view showing a sealing operationbeing a subordinate operation in the light emitting element disposingoperation in the method of manufacturing the light emitting deviceaccording to the first embodiment;

FIG. 8A is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 8B is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 9A is a schematic plan view showing the configuration of;

FIG. 9B is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 9C is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 9D is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 9E is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 9F is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10A is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10B is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10C is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10D is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10E is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 10F is a schematic plan view showing the configuration of a lightemitting device according to Variation of the first embodiment;

FIG. 11A is a schematic plan view showing the configuration of a lightemitting device according to a second embodiment;

FIG. 11B is a schematic plan view showing the configuration of a lightemitting element in the light emitting device according to the secondembodiment;

FIG. 12A is a schematic plan view for describing disposition of lightemitting elements used in simulating the luminous flux of the lightemitting device according to the second embodiment;

FIG. 12B is a schematic plan view for describing disposition of lightemitting elements in simulating the luminous flux of the light emittingdevice according to Comparative Example;

FIG. 13 is a graph showing the simulation results of the luminous fluxof the light emitting device according to the second embodiment and thelight emitting device according to Comparative Example; and

FIG. 14 is a schematic plan view showing the configuration of a lightemitting device according to a third embodiment.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

In the following, a description will be given of a light emitting deviceand a method of manufacturing the light emitting device according toembodiments. Note that, since the drawings referred to in the followingdescription schematically show the embodiments, the scale, intervals, orpositional relationship of the constituent elements may be exaggerated,or part of the constituent elements may not be shown. Further, forexample between a plan view and a corresponding cross-sectional view,the scale or intervals of the constituent elements may not be common.Still further, in the following description, identical names andreference characters denote identical or similar constituent elements onprinciple, and detailed description are omitted as appropriate.

Further, in connection with the light emitting device and the method ofmanufacturing the light emitting device according to the embodiments,“top/upper”, “bottom/lower”, “left”, and “right” are to be replaced byone another according to the situation. In the present specification,“top/upper”, “bottom/lower” and the like refer to the relative positionsbetween the constituent elements in the drawings referred to for anexplanation, and are not intended to specify absolute positions unlessotherwise stated.

First Embodiment

Configuration of Light Emitting Device

With reference to FIGS. 1A to 1D, a configuration of a light emittingdevice according to a first embodiment. FIG. 1A is a schematicperspective view showing the configuration of the light emitting deviceaccording to the first embodiment. FIG. 1B is a schematic plan viewshowing the configuration of the light emitting device according to thefirst embodiment. FIG. 1C is a schematic cross-sectional view showingthe configuration of the light emitting device according to the firstembodiment, being a cross-sectional view taken along line IC-IC in FIG.1B. FIG. 1D is a schematic cross-sectional view showing theconfiguration of the light emitting device according to the firstembodiment, being a cross-sectional view taken along line ID-ID in FIG.1B.

A light emitting device 100 according to the first embodiment includestwo light emitting elements 1 and a package 2, each of the lightemitting elements 1 having a hexagonal shape in a plan view.

The light emitting elements 1 are arranged on a bottom surface of arecess 23 a formed in an upper surface of the package 2, and the lightemitting elements 1 are electrically connected to lead electrodes 21, 22via wires 4, where the lead electrodes 21, 22 are disposed to form mostportion of the bottom surface 23 b of the recess 23 a. The lightemitting elements 1 are each bonded to the bottom surface 23 b of therecess 23 a using a die bonding resin 61. Further, a protective element5 is provided in the recess 23 a, and is electrically connected to thelead electrodes 21, 22 via an electrically conductive joining member 62and the wire 4. Further, in the recess 23 a, a light transmissivesealing resin 3 is provided, so as to seal the light emitting elements 1and the protective element 5.

Further, light generated by each of the light emitting elements 1 isemitted upward from the opening of the recess 23 a through the lighttransmissive sealing resin 3.

Note that, in FIGS. 1A and 1B, shading represents the existence of thesealing resin 3 in the recess 3 a.

The light emitting elements 1 are bonded to the lead electrode 21 of onepolarity provided at the bottom surface 23 b of the recess 23 a openingat the upper surface of the package 2 using the die bonding resin 61.Further, the positive and negative pad electrodes (the anode and thecathode) of each light emitting element 1 are electrically connected tothe lead electrodes 21, 22 of corresponding polarity, via bonding wires4 made of, for example, Au, Ag, Cu, or Al.

Further, in the example shown in the figures, two light emittingelements 1 are mounted, but three or more light emitting elements 1 canalso be mounted. The plurality of light emitting elements may emit lightof the same or different colors.

Next, with reference to FIGS. 2A and 2B, a configuration of a singlelight emitting element 1 will be described. FIG. 2A is a schematic planview showing a configuration of one light emitting element in the lightemitting device according to the first embodiment. FIG. 2B is aschematic cross-sectional view showing the configuration of the lightemitting element in the light emitting device according to the firstembodiment, taken along line IIB-IIB in FIG. 2A.

Note that, in the present embodiment, since the light emitting device100 is of the top-view type, the light emitting element 1 is mountedsuch that the main surface of a substrate 11 is in parallel to the uppersurface of the light emitting device 100, that is, in parallel to thebottom surface 23 b of the recess 23 a.

As the light emitting element 1, a semiconductor light emitting elementsuch as an LED can be suitably used. The light emitting element 1according to the present embodiment is formed into an approximatelyregular hexagon in a plan view, and includes the substrate 11, asemiconductor stacked-layer body 12, an n-side electrode 13, a p-sideelectrode 14, and a protective film 15. In more detail, the lightemitting element 1 according to the present embodiment includes, on onemain surface of the substrate 11, the semiconductor stacked-layer body12 having a light emitting diode “LED” configuration, and further, then-side electrode 13 and the p-side electrode 14 are disposed on onesurface side of the semiconductor stacked-layer body 12. Thus, the lightemitting element 1 has the configuration suitable for face-up typemounting.

The outer shape of the light emitting element 1 in a plan view is anapproximately regular hexagon. Accordingly, when a plurality of lightemitting elements 1 are mounted, the light emitting elements 1 can bedisposed such that, at least part of the plurality of light emittingelements are disposed so that mutually facing lateral sides of adjacentones of the light emitting elements are not in parallel to each other.

Note that, the outer shape in a plan view of the light emitting element1 is not limited to an approximately regular hexagon, and may be aconvex polygon of at least five sides whose interior angles are all lessthan 180 degrees. Other exemplary outer shape in a plan view of thelight emitting element 1 will be described later.

In the present specification, the expressions the lateral side surfacesof the light emitting elements 1 being “parallel” or “substantiallyparallel” to each other includes the case where the inclination anglefrom the parallel reference is 10° or smaller.

The substrate 11 is a substrate suitable for epitaxially growing thesemiconductor stacked-layer body 12 thereon. The substrate 11 may be,for example, in the case of forming the semiconductor stacked-layer body12 with a nitride semiconductor such as GaN (gallium nitride), aninsulating substrate of a sapphire with a principal plane being C-plane,R-plane, or A-plane, and a spinel (MgAl₂O₄), or an oxide substrate suchas lithium niobate or neodymium gallate that forms lattice bonds withsilicon carbide (SiC), ZnS, ZnO, Si, GaAs, diamond, and a nitridesemiconductor.

The semiconductor stacked-layer body 12 is made of an n-typesemiconductor layer 12 n and a p-type semiconductor layer 12 p stackedon one main surface that is the upper surface of the substrate 11. Thesemiconductor stacked-layer body 12 is configured to emit light uponapplication of electric current between the n-side electrode 13 and thep-side electrode 14. The semiconductor stacked-layer body 12 preferablyincludes an active layer 12 a between the n-type semiconductor layer 12n and the p-type semiconductor layer 12 p.

In the semiconductor stacked-layer body 12, a region absent of thep-type semiconductor layer 12 p and the active layer 12 a, that is, astep portion 12 b recessed from the surface of the p-type semiconductorlayer 12 p is formed. The bottom surface of the step portion 12 b isformed by the n-type semiconductor layer 12 n. In the presentembodiment, in FIG. 2A, the step portion 12 b is formed to extendgenerally semicircularly around the center portion of the light emittingelement, from a portion near the right end of the light emitting element1 in the figure.

The n-side electrode 13 is mounted on the bottom surface of the stepportion 12 b and electrically connected to the n-type semiconductorlayer 12 n.

Also, a step portion 12 c absence of the p-type semiconductor layer 12 pand the active layer 12 a is also formed at an outer edge portion of thelight emitting element 1. The step portion 12 c is a part of a dicingstreet that is a cutting region used in singulating individual lightemitting elements 1 from a wafer.

Further, a light transmissive electrode 141 is disposed on substantiallythe entire upper surface of the p-type semiconductor layer 12 p as alower layer of the p-side electrode 14, and a pad electrode 142 isdisposed a portion of the upper surface of the light transmissiveelectrode 141 as an upper layer of the p-side electrode 14. In addition,the surfaces of the semiconductor stacked-layer body 12, the n-sideelectrode 13 and the p-side electrode 14 are covered by a protectivefilm 15, except for an external connection portion 13 a of the n-sideelectrode 13 and an external connection portion 142 a of the padelectrode 142 of the p-side electrode 14.

Examples of suitable semiconductor stacked-layer body 12,includestacked-layers of semiconductors such as ZnS, SiC, GaN, GaP, InN, AlN,ZnSe, GaAsP, GaAlAs, InGaN, GaAlN, A1InGaP, and AlInGaN provided on asubstrate, formed by using a liquid phase growing method, a HDVPEmethod, a MOCVD method, or the like. As to the semiconductor material, agallium nitride-based semiconductor represented byIn_(X)Al_(Y)Ga_(1-x-y)N (0≦X, 0≦Y, X+Y<1) can be more suitably used,because any light emission wavelength ranging from ultraviolet light toinfrared light can be selected by selecting a mixed crystal ratio.

The n-side electrode 13 is electrically connected to the n-typesemiconductor layer 12 n at the bottom surface of the step portion 12 bof the semiconductor stacked-layer body 12. The n-side electrode 13 is anegative pole for supplying external current to the light emittingelement 1. Further, in the plan view of FIG. 2A, the n-side electrode 13has the external connection portion 13 a at a portion near the right endof the light emitting element 1, and has an extending portion 13 bextending from the external connection portion 13 a toward the externalconnection portion 142 a of the p-side pad electrode 142.

The n-side electrode 13 may be made of, for example, Cu, Au or an alloycontaining Cu or Au as a main component, in order to be suitable forconnecting to the outside by way of wire bonding or the like.

Further, a lower layer portion of the n-side electrode 13 may be made ofa material having good reflectivity to the wavelength of light emittedfrom the semiconductor stacked layer body 12, for example, Al, Ru, Ag,Ti, Ni, or an alloy containing one of those as a main component. Thus,light emitted from the semiconductor stacked layer body 12 andpropagating inside the semiconductor stacked layer body 12 and incidenton the lower surface of the n-side electrode 13 can be reflected at thelower surface of the n-side electrode 13 so as to reduce absorption oflight by the n-side electrode 13 and increase the light extractingefficiency to the outside.

The p-side electrode 14 is a positive electrode disposed electricallyconnected to the upper surface of the p-type semiconductor layer 12 p tosupply external current to the light emitting element 1. The p-sideelectrode 14 includes the light transmissive electrode 141 and the padelectrode 142 formed on the light transmissive electrode 141.

The light transmissive electrode 141 that is the lower layer of thep-side electrode 14 is disposed on substantially the entire uppersurface of the p-type semiconductor layer 12 p. The light transmissiveelectrode 141 functions as a current diffusion layer to diffuse currentthat is externally supplied via the pad electrode 142 to the entirep-type semiconductor layer 12 p. Further, the light emitted by thesemiconductor stacked-layer body 12 is extracted to the outside mainlyvia the light transmissive electrode 141. Therefore, the lighttransmissive electrode 141 preferably has a high light transmissiveproperty to the wavelength of the light emitted by the semiconductorstacked-layer body 12.

The light transmissive electrode 141 is formed by an electricallyconductive metal oxide. The electrically conductive metal oxide may beoxide containing at least one element selected from a group consistingof Zn (zinc), In (indium), Sn (tin), Ga (gallium) and Ti (titanium).Specifically, the electrically conductive metal oxide may be ZnO,Al-doped ZnO “AZO”, In-doped ZnO “IZO”, Ga-doped ZnO “GZO”, In₂O₃,Sn-doped In₂O₃ “ITO”, F-doped In₂O₃ “IFO”, SnO₂, Sb-doped SnO₂ “ATO”,F-doped SnO₂ “FTO”, Cd-doped SnO₂ “CTO”, or TiO₂.

Among others, ITO has high light transmissive property to visible light(in the visible region) and exhibits high electrical conductivity.Therefore, ITO is a material suitable for covering substantially theentire upper surface of the p-type semiconductor layer 12 p.

The pad electrode 142, which is the upper layer, is a layer configuredto connect to an external electrode, and disposed on a portion of theupper surface of the light transmissive electrode 141. Further, the padelectrode 142 includes the external connection portion 142 a forconnecting to the outside via a wire or the like, and an extendingportion 142 b extending from the external connection portion 142 a. Theextending portion 142 b is provided toward the external connectionportion 13 a of the n-side electrode 13 and to surround the extendingportion 13 b so that the current can be diffused more efficiently.

Similarly to the n-side electrode 13, the pad electrode 142 may be madeof, for example, Cu, Au or an alloy containing Cu or Au as a maincomponent, in order to be suitable for connecting to the outside by wayof wire bonding or the like.

Note that, in the present embodiment, the pad electrode 142 includes theexternal connection portion 142 a and the extending portion 142 b madeof the same material.

Further, an insulating film may be disposed on the p-type semiconductorlayer 12 p in a region immediately below the region where the padelectrode 142 is disposed and its vicinity in a plan view. With theinsulating film provided in this manner, the current flowing through thep-type semiconductor layer 12 p immediately below the pad electrode 142can be reduced, and the light emission at such region can be reduced.Accordingly, the amount of light propagating toward the pad electrode142 can be reduced, so that the amount of light absorbed by the padelectrode 142 can be reduced, and as a result, the light emission amountof the semiconductor stacked-layer body 12 as a whole can be increased.The insulating film is preferably light transmissive and, for example,an oxide such as SiO₂, TiO₂, or Al₂O₃, a nitride such as SiN, or afluoride such as MgF can be used suitably.

The protective film 15 is a light transmissive insulating film, disposedon approximately the entire upper surface and lateral side surfaces ofthe light emitting element 1 except for the lateral side surfaces andthe lower surface of the substrate 11. Further, the protective film 15has an opening 15 n at the upper surface of the n-side electrode 13, andhas an opening 15 p at the upper surface of the pad electrode 142. Theregions respectively exposed at the openings 15 n, 15 p serve asexternal connection portions 13 a, 142 a.

For the protective film 15, an oxide such as SiO₂, TiO₂, or Al₂O₃, anitride such as SiN, or a fluoride such as MgF can be used suitably.

Note that, in the light emitting element 1, configurations such as thelocations and,shapes, and the configurations of the layers and so forthof the n-side electrode 13 and the p-side electrode 14 and the like, andthe locations and the shapes and so forth of the step portion 12 b andthe like are not limited to that exemplified in the present embodiment,and can be determined as appropriate.

Further, in FIGS. 1A to 1D, for the simplicity of explanation, only thepositive and negative external connection portions 13 a, 142 a are shownas the n-side electrode 13 and the p-side electrode 14 of the lightemitting element 1.

Referring back to FIGS. 1A to 1D, the description of the light emittingdevice 100 is continued.

The package 2 includes the lead electrodes 21, 22 and the resin part 23.The package 2 has an outer shape of approximately quadrangular prismshape flat in the thickness direction of the light emitting device 10,with an approximately square shape in a plan view. The package 2 definesa recess 23 a that opens in the upper surface and the light emittingelements 1 are mounted in the recess 23 a so that light is emitted fromthe opening of the recess, and thus the package 2 is suitable fortop-view type mounting.

The lead electrode 21 and the lead electrode 22 are a pair of electrodescorresponding to positive and negative polarity. The lead electrodes 21,22 are disposed so as to be supported by the resin part 23, and theupper surfaces of the lead electrodes 21, 22 configuration the bottomsurface 23 b of the recess 23 a. To the upper surface of the leadelectrode 21, two light emitting elements 1 are bonded by the diebonding resin 61. The two light emitting elements 1 are electricallyconnected in series between the lead electrodes 21, 22 by the wires 4.Further, to the upper surface of the lead electrode 22, the protectiveelement 5 is bonded by the joining member 62, and electrically connectedbetween the lead electrodes 21, 22 by the wire 4 and the electricallyconductive joining member 62.

Further, the lower surfaces of the lead electrodes 21, 22 are themounting surface of the light emitting device 100 for establishingexternal connection. Accordingly, the light emitting device 100 ismounted such that the bottom surface of the light emitting device isplaced opposite to the mounting substrate and the lower surfaces of thelead electrodes 21, 22 are bonded to the wiring pattern of the mountingsubstrate by an electrically conductive joining member such as a solder.

The lead electrodes 21, 22 are each made of plate-like metal. Thethickness of the lead electrodes 21, 22 may be uniform or partiallythick or thin.

The material of the lead electrodes 21, 22 is not specifically limited,but a material having a relatively great thermal conductivity ispreferably used. By employing such a material, the heat generated at thelight emitting elements 1 can be efficiently released to the outside viathe lead electrodes 21, 22. Preferable material of the lead electrodes21, 22 has a thermal conductivity of, for example, about 200 W/(m·K) orgreater, and relatively great mechanical strength or good processabilityin press working or etching. Alternatively, the material with whichpunching press work or etching work can be easily performed ispreferable. Examples of such a materias include a metal such as copper,aluminum, gold, silver, tungsten, iron, and nickel, and an alloy such asiron-nickel alloy and phosphor bronze. Further, portions of the leadelectrodes 21, 22 that are exposed as the bottom surface 23 b of therecess 23 a are preferably provided with a reflective-plating of Ag orthe like having a high light reflectivity, for the purpose ofefficiently extracting light from the light emitting elements 1 that aremounted thereon.

The resin part 23 is a base body of the package 2 for supporting thelead electrodes 21, 22. The resin part 23 defines the recess 23 a in theupper surface. The bottom surface 23 b of the recess 23 a is mainlyformed with the surfaces of the lead electrodes 21, 22 that provide amounting surface. Further, on the lower surface side of the resin part23, the lead electrodes 21, 22 are exposed, to function as the mountingsurface.

On the lead electrodes 21, 22, which are the bottom surface 23 b of therecess 23 a, two light emitting elements 1 and one protective element 5are respectively mounted. The lateral side surfaces defining the recess23 a are inclined such that the recess 23 a is widened upward so thatlight emitted from the light emitting element in directions toward thelateral sides can be reflected upward, which is the light extractingdirection.

Further, in a plan view, the recess 23 a is formed with an opening of anapproximately square with one rounded corner, which serves as a cathodemark 23 c for distinguishing the polarity of the lead electrodes 21, 22.

The resin part 23 is made of a light transmissive resin having lightreflectivity, which is obtained by containing particles of a lightreflective material, so that the resin part 23 also serves as a lightreflecting member. The resin part 23 also functions as a lightreflective member in the recess 23 a for reflecting the light from thelight emitting elements 1 upward efficiently.

Further, the light transmissive sealing resin 3 is filled in the recess23 a.

The resin material used for the material of the resin part 23 preferablyhas good light transmissive property to the wavelength of light emittedby the light emitting elements 1, and a thermosetting resin, athermoplastic resin or the like can be used. Exemplary thermosettingresin may be silicone resin, silicone-modified resin, silicone hybridresin, epoxy resin, epoxy-modified resin, urea resin, diallyl phthalateresin, phenol resin, unsaturated polyester resin, or hybrid resincontaining at least one of the foregoing resins. Exemplary thermoplasticresin may be polycarbonate resin, acrylic resin, polymethylpenteneresin, polynorbornene resin, polyphthalamide resin, polyester resin,liquid crystal resin, polyphenylene ether resin, aromatic polyamideresin, or hybrid resin containing at least one of the foregoing resins.Among those, polyester resin such as polycyclohexylenedimethyleneterephthalate “PCT”, aromatic polyamide resin, epoxy resin, unsaturatedpolyester resin, silicone resin, and silicone hybrid resin exhibitinggood heat-resistance and lightfastness are preferable.

The light reflective substance contained in the resin part 23 ispreferably particles of a material having a large difference in index ofrefraction from the above-described resin material and has good lighttransmissive property.

Such a light reflective substance preferably has an index of refractionof 1.8 or more for example. In order to efficiently scatter light and toattain high light extraction efficiency, the index of refraction ispreferably 2.0 or more and more preferably 2.5 or more. The differencein the refractive index with respect to that of the resin material is,for example, 0.4 or greater, and in order to efficiently scatter lightand to attain high light extraction efficiency, the difference ispreferably 0.7 or greater, and more preferably 0.9 or greater. Further,the average particle size of the particles of the light reflectivesubstance is preferably in a range of 0.08 μm to 10 μm inclusive, andmore preferably in a range of 0.1 μm to 5 μm inclusive, in order toefficiently scatter light and to attain high light extractionefficiency.

Note that, in the present specification, the values of average particlesize of particles of the light reflective substance, the wavelengthconverting substance and the like are obtained by observation throughuse of an electron microscope. Particles are measured in a certain axisdirection, and by number-based measurement (number-based distribution)in which the size of the particles is measured using an electronmicroscope (SEM, TEM).

Further, as the light reflective substance, specifically, particles ofwhite pigment such as TiO₂ (titanium oxide), ZrO₂ (zirconium oxide), MgO(magnesium oxide), MgCO₃ (magnesium carbonate), Mg(OH)₂ (magnesiumhydroxide), CaCO₃ (calcium carbonate), Ca(OH)₂ (calcium hydroxide),CaSiO₃ (calcium silicate), ZnO (zinc oxide), BaTiO₃ (barium titanate),and Al₂O₃ (aluminum oxide) can be used. Among those, TiO₂ is preferable,because TiO₂ is relatively stable to moisture or the like, and has ahigh index of refraction and good thermal conductivity.

Further, in order to obtain better reflectivity, when light emitted bythe light emitting elements 1 is visible light, preferably TiO₂ isemployed as the light reflective substance, and when the light isultraviolet light, preferably Al₂O₃ is used as the light reflectivesubstance.

Still further, the resin material contains the light reflectivesubstance in a range with which full light reflectivity is obtained andwith which moldability in forming the package is not impaired. For that,the content of the light reflective substance in the resin part 23 ispreferably in a range of 10 mass % to 60 mass % inclusive. With thecontent value of 10 mass % or more, the reflectivity of the resin can beincreased. Thus, light leakage from the resin part 23 can be reduced,and the light extraction efficiency can be improved. By employing thevalue of 60 mass % or less, flowability of the resin can be improved,and moldability can be improved. In view of an improvement in the lightextraction efficiency and in moldability, the content of the lightreflective substance in the resin part 23 is more preferably in a rangeof 10 mass % to 50 mass % inclusive.

The sealing resin 3 is a member having a light transmissive resinmaterial as its main component, and disposed to fill the recess 23 a ofthe resin part 23 to seal the light emitting elements 1 and theprotective element 5 mounted on the bottom surface 23 b of the recess 23a, respectively. Further, the sealing resin 3 may contain a wavelengthconverting substance (a fluorescent material) that converts the lightemitted by the light emitting element 1 into light of differentwavelength. For example, with a configuration where blue light isemitted by the light emitting element 1, and a portion of the blue lightis converted by the wavelength converting substance into yellow light,it becomes possible to emit white light that is a mixture of the bluelight and the yellow light from the light emitting device 100.

Note that, a plurality of types of wavelength converting substances maybe contained in the sealing resin 3. In place of or in addition to thewavelength converting substance, a light diffusing substance may becontained.

The sealing resin 3 is preferably made of a material that exhibits goodlight transmissive property to the wavelength of light emitted by thelight emitting elements 1 and to the wavelength of light emitted by thewavelength converting substance, and exhibits good weather resistance,lightfastness and heat-resistance as the sealing member. As such amaterial, a resin material similar to that employed for the resin part23 described above, or glass can be employed. Exemplary materials of thesealing resin 3 may include silicone resin, silicone-modified resin,silicone hybrid resin, fluororesin, fluoro-modified resin, adamantaneresin and the like. In particular, silicone resin and fluoro resin arepreferable for their high heat-resistance and light resistance. Siliconeresin of which index of refraction is 1.4 to 1.6 is preferable. Inparticular, silicone resin of which index of refraction is 1.41 to 1.55is more preferable for its high heat-resistance, light resistance, lightextraction characteristic, gas barrier characteristic and sulfidationresistance, and well-balanced quality to be used with an LED.

Further, as the wavelength converting substance (the fluorescentmaterial), any substance known in the art can be employed. Exemplarysubstances include a cerium-activated YAG (yttrium-aluminum-garnet)-basefluorescent material emitting green to yellow-color light, acerium-activated LAG (lutetium-aluminum-garnet)-base fluorescentmaterial emitting green-color light, an europium and/orchromium-activated nitrogen-containing calcium aluminosilicate(CaO—Al₂O₃—SiO₂)-base fluorescent material emitting green to red-colorlight, an europium-activated silicate ((Sr, Ba)₂SiO₄)-base fluorescentmaterial emitting blue to red-color light, β sialon fluorescent materialand a sulfide fluorescent material represented by SrGa₂S₄:Eu emittinggreen-color light, a nitride-based fluorescent material such as aCASN-base fluorescent material represented by CaAlSiN₃:Eu or aSCASN-base fluorescent material represented by (Sr,Ca)AlSiN₃:Eu emittingred-color light, a K₂SiF₆:Mn (KSF)-base fluorescent material emittingred-color light, and a sulfide-base fluorescent material emittingred-color light.

Further, as the light diffusing substance, a material similar to thatemployed for the light reflective substance can be employed.

In the case where the die area in a plan view is identical, a polygonaldie having five or more corners is greater than a quadrangular die inthe total area of the side surfaces. Therefore, the light from the lightemitting element 1 can be efficiently emitted to the wavelengthconverting substance. Accordingly, it becomes possible to disperse thewavelength converting substance around the light emitting element 1 todisperse the emitted heat, and to reduce the use amount of thewavelength converting substance. Hence, deterioration from the heat ofthe wavelength converting substance can be suppressed, and thereliability of the light emitting device 100 can be improved. Inparticular, it is extremely effective to the light emitting deviceincluding a sulfide-base, fluoride-base, or nitride-based fluorescentmaterial which tends to deteriorate by heat, and heat emission and theuse amount of the wavelength converting substance can be reduced toimprove the reliability of the light emitting device 100.

Further, as the light diffusing substance contained in the sealing resin3, specifically, particles of white pigment such as SiO₂, TiO₂, ZrO₂,MgO, MgCO₃, Mg(OH)₂, CaCO₃, Ca(OH)₂, CaSiO₃, ZnO, BaTiO₃, Al₂O₃ and thelike can be employed.

The average particle size of the particles of the light diffusingsubstance contained in the sealing resin 3 is preferably from 0.001 μmto 10 μm inclusive. This provides a highly efficient light scatteringcharacteristic. In particular, the average particle size of theparticles of the light diffusing substance in the sealing resin 3 ismore preferably from 0.001 μm to 0.05 μm inclusive. This provides a highlight scattering effect, that is, the Rayleigh scattering effect and theeffect of rendering the dispersion state of the wavelength convertingsubstance uniform. Thus, the light extraction efficiency of the lightemitting device 100 can be further improved.

Further, by using the particles of the light diffusing substance ofwhich average particle size is preferably in a range of 0.001 μm to 0.05μm and the above-described wavelength converting substance, particularlythe nitride-based fluorescent material such as CASN-base or SCASN-base,the fluoride-base fluorescent material such as KSF-base, and thesulfide-base fluorescent material in combination, the light extractionefficiency can be improved. By virtue of the uniformly dispersedwavelength converting substance and the improved light extractionefficiency, the use amount of the wavelength converting substance can bereduced, whereby an increase in the temperature by the heat emission ofthe wavelength converting substance can be suppressed. Thus,deterioration of the wavelength converting substance can be reduced, andthe reliability of the light emitting device 100 can be improved.

In particular, with the light emitting device 100 having the lightemitting elements 1 each being a polygonal die having five of morecorners, including a sulfide-base, fluoride-base or nitride-basedfluorescent material as the wavelength converting substance, andcontaining the light diffusing substance of which average particle sizeis 0.001 μm to 10 μm, deterioration of the sealing resin 3 or thefluorescent material can be reduced, or the light extraction efficiencycan be improved.

The wires 4 electrically connect between the external connection portion13 a of the n-side electrode 13 of one light emitting element 1 and theexternal connection portion 142 a of the p-side electrode 14 of otherlight emitting element 1, between the external connection portion 142 aof other light emitting element 1 and the lead electrode 21 ofcorresponding polarity, and between the external connection portion 13 aand the lead electrode 22 of corresponding polarity. Further, the wire 4is also used to electrically connect between the one electrode of theprotective element 5 and the lead electrode 21.

The wires 4 can suitably be made of Au, Cu, Al, or Ag or an alloycontaining one of those as a main component.

It is preferable to provide the protective element 5 for protecting thelight emitting element 1 from electrostatic discharge. As the protectiveelement 5, a Zener diode may be connected to the light emitting element1 in parallel and with reverse polarity. Further, as the protectiveelement 5, a varistor, a resistor, a capacitor or the like can also beused.

The protective element 5 is bonded on the lead electrode 22 using thejoining member 62 having electrical conductivity, whereby one electrodeof the protective element 5 is electrically connected to the leadelectrode 22. Further, other electrode of the protective element 5 isconnected to the lead electrode 21 using the wire 4.

The die bonding resin 61 is a bonding member for bonding each lightemitting element 1 to the lead electrode 21 provided at the bottomsurface 23 b of the recess 23 a.

The die bonding resin 61 is preferably a resin material that is lessprone to discolor or deteriorate by the light or heat emitted by thelight emitting elements 1, having good light transmissive property, andhaving an index of refraction equal to or smaller than that of thesealing resin 3. By setting the index of refraction of the die bondingresin 61 to be equal to or smaller than that of the sealing resin 3, thelight output from the light emitting element 1 via the die bonding resin61 will not be totally reflected at the interface between the diebonding resin 61 and the sealing resin 3, and can be efficientlyextracted to the outside. As such a resin material, a silicone-base diebonding resin having the siloxane skeleton is preferable. Exemplarysilicone-base die bonding resins include silicone resin, silicone hybridresin, and silicone-modified resin.

In particular, a combination of a polygonal die having five or morecorners and a silicone die bonding resin of which index of refraction isequal to or smaller than that of the sealing resin 3 is extremelyeffective. The lateral side surface area of a polygonal die having fiveor more corners is greater than that of a quadrangular die. Therefore,the amount of light output from the light emitting element 1 is alsogreater, and can be efficiently extracted to the outside.

The joining member 62 is an electrically conductive adhesive agent suchas solder for joining the protective element 5 to the lead electrode 22and electrically connecting one electrode of the protective element 5and the lead electrode 22 to each other.

Operation of Light Emitting Device

Next, with reference to FIG. 1B, a description will be given of theoperation of the light emitting device 100.

Note that, for the sake of convenience, it is assumed that the lightemitting elements 1 emit blue-color light, and the sealing resin 3contains the wavelength converting substance that absorbs the blue-colorlight and emits yellow-color light.

When the light emitting device 100 is connected to the external powersupply via the lead electrodes 21, 22, current is supplied to the lightemitting elements 1 via the wires 4, and the light emitting elements 1emit blue-color light. The blue-color light emitted by the lightemitting elements 1 is partially converted to yellow-color light by thewavelength converting substance while propagating through the sealingresin 3. Then, the blue-color light and the yellow-color light arepartially reflected and partially absorbed at the interfaces of thelight emitting elements 1, the die bonding resin 61, the lead electrodes21, 22, the resin part 23, and the sealing resin 3 provided in therecess 23 a, and output as white-color light being the mixture of theblue-color light and the yellow-color light from the opening of therecess 23 a of the package 2.

More specifically, part of the light output from the lateral sidesurfaces of one light emitting element 1 and propagating in thedirection parallel to the bottom surface 23 b in the sealing resin 3illuminates the lateral side surfaces of the recess 23 a and reflectedupward, thereby extracted to the outside. Further, other part of thelight enters the adjacent other light emitting element 1 from thelateral side surfaces of the adjacent light emitting element 1. Thoughthe light entering the light emitting elements 1 is partially extractedto the outside by the route described above, the remainder is absorbedin the light emitting elements 1. This causes a reduction in the lightextraction efficiency. In particular, in the case where one of thelateral sides of adjacent two light emitting elements 1 are arranged inparallel to each other, the amount of light emitted from one lightemitting element 1 entering the adjacent light emitting elements 1increases.

In the present embodiment, the two light emitting elements 1 each havean outer shape of an approximately regular hexagon in a plan view. Thelight emitting elements 1 are disposed such that the lateral sides ofrespective approximately regular hexagons oppose to each other not inparallel. Therefore, the proportion of the light output from the lateralside surfaces of one light emitting element 1 entering other lightemitting element can be reduced. Therefore, the amount of light absorbedin the light emitting elements 1 reduces, and consequently the lightextraction efficiency to the outside improves.

Further, as compared to the case where light emitting elements havingsquare outer shape are arranged at positions rotated by 45° about anaxis perpendicular to the main surface, the proportion of the area ofthe light emitting elements per area required for the arrangement can beincreased. That is, such an outer shape of the light emitting elements 1and disposition of the light emitting elements 1 in the recess 23 a canimprove the mounting efficiency, in terms of area, of the light emittingelements 1 in the mounting region of the package 2. Therefore, despitethe package 2 being of the conventional size, the output of the lightemitting device 100 can be increased. Further, in place of or inaddition to the increase in the output of the light emitting device 100,the size of the light emitting device 100 can be reduced than theconventional light emitting device.

Comparative Experiment of Luminous Flux

Next, with reference to FIG. 1B and FIGS. 3A to 4C, a description willbe given of an experiment in which comparison is made as to the luminousflux output from the light emitting devices each mounting two lightemitting elements, the light emitting devices differing from each otherin the shape and disposition of the light emitting elements.

FIG. 3A is a schematic plan view showing the configuration of a lightemitting device according to Reference Example. FIG. 3B is a schematicplan view showing the configuration of the light emitting deviceaccording to Reference Example. FIG. 4A is a schematic plan view showingthe configuration of a light emitting device according to ExperimentalExample. FIG. 4B is a schematic plan view showing the configuration ofthe light emitting device according to Experimental Example. FIG. 4C isa schematic plan view showing the configuration of a light emittingdevice according to Comparative Example.

In the present experiment, what were prepared were light emittingdevices 100, 100A, 100B according to Experimental Examples of the firstembodiment in each of which two light emitting elements 1 of which outershape is an approximately regular hexagon were mounted, and a lightemitting device 1100 according to Comparative Example in which two lightemitting elements 1001 of which outer shape was approximately squarewere mounted. The luminous flux of the output light of the lightemitting devices 100, 100A, 100B, 1100 was measured and the lightemitting devices 100, 100A, 100B, 1100 were compared against each otheras to the luminous flux.

Further, as Reference Examples, a light emitting device 110 in which onelight emitting element 1 was mounted and a light emitting device 1110 inwhich one light emitting element 1001 was mounted were prepared, and thelight emitting device 110 and the light emitting device 1110 werecompared against each other as to the luminous flux.

Note that, the light emitting devices 100A, 100B are Variations of thelight emitting device 100 according to the first embodiment.

Further, the light emitting element 1 and the light emitting element1001 have outer shapes of approximately the same planar dimensions. Thelight emitting element 1001 has an approximately square outer shape witha side of about 612 μm. The wires 4 are provided so that the length ofthe wires are approximately the same at the corresponding portions ofthe light emitting device 110 and the light emitting device 1110. Thelight emitting elements 1, 1001 each has a thickness of about 150 μm andthe opening width of the recess of the package 2 of about 2.6 mm.

When the luminous flux of the light emitting device 1110 in which onelight emitting element 1001 is mounted was 100%, the luminous flux ofthe light emitting device 110 in which one light emitting element 1 wasmounted was 99.95%, and thus it was confirmed that they exhibitedpractically the same luminous flux.

In the light emitting device 1100 illustrated as Comparative Example,two light emitting elements 1001 are disposed such that one sides of theapproximately square outer shapes of the light emitting elements 1001are arranged facing each other in parallel in a plan view.

Further, in the light emitting device 100A, two light emitting elements1 are disposed such that respective one sides of the approximatelyregular hexagonal outer shapes of the light emitting elements 1 arearranged facing each other in parallel in a plan view. Here, theexternal connection portion of the n-side electrode 13 and the externalconnection portion of the p-side electrode 14 are disposed so as to bein parallel to the above-described one sides of the outer shapehexagons, and the length of the wire 4 connecting between the lightemitting elements 1 is substantially identical to that in the lightemitting device 1100.

When the luminous flux of the light emitting device 1100 was 100%, theluminous flux of the light emitting device 100A was about 100.2%, andthus it was found that the output of the light emitting device 100A wasimproved as compared to the light emitting device 1100.

Similarly to the light emitting device 100A, in the light emittingdevice 100B, two light emitting elements 1 are disposed such thatrespective one sides of the approximately regular hexagonal outer shapesof the light emitting elements 1 are arranged facing each other inparallel in a plan view. Here, the length of the wire 4 connectingbetween the light emitting elements 1 are shorter than that in the lightemitting device 100A, because the light emitting elements 1 are disposedsuch that the external connection portion of the n-side electrode 13 ofthe left light emitting element 1 and the external connection portion ofthe p-side electrode 14 of the right light emitting element 1 are inclose proximity to each other.

The luminous flux of the light emitting device 100B was about 100.6%,and it was found that the output was improved as compared to the lightemitting device 100A.

In this manner, by shortening the wiring length of the wire 4 connectingbetween the light emitting elements 1, absorption or reflection of lightby the wire 4 is suppressed, whereby the light extraction efficiency canbe improved.

As has been described above, in the light emitting device 100, two lightemitting elements 1 are disposed such that respective one corner of theapproximately regular hexagonal outer shape of the light emittingelements 1 in a plan view are facing each other while facing sides arenot in parallel to each other. Here, the external connection portion ofthe n-side electrode 13 and the external connection portion of thep-side electrode 14 respectively provided around the vertexes in closeproximity to each other are connected to each other by the wire 4. Thus,the light emitting elements 1 are disposed such that the wiring lengthof the wire 4 between the light emitting elements 1 is almost minimized.

The luminous flux of the light emitting device 100 was about 101.5%, andit was found that the output was further improved even as compared tothe light emitting device 100B.

As described above, by the present experiment, it was found that theoutput becomes greater as respective lateral side surfaces of theadjacent light emitting elements 1 oppose to each other in parallel by asmaller area, and further preferably as the wiring length of the wire 4connecting between the light emitting elements 1 is shorter.

Method of Manufacturing Light Emitting Device

Next, with reference to FIGS. 5A to 7C, a description will be given of amethod of manufacturing the light emitting device 100.

FIG. 5A is a flowchart showing the procedure of the method ofmanufacturing the light emitting device according to the firstembodiment. FIG. 5B is a flowchart showing details of a light emittingelement disposing operation in the method of manufacturing the lightemitting device according to the first embodiment. FIG. 6A is aschematic plan view showing boundary lines virtually partitioning awafer in a light emitting element preparing operation in the method ofmanufacturing the light emitting device according to the firstembodiment. FIG. 6B is a schematic plan view showing the state wherelight emitting elements are formed on the wafer in the light emittingelement preparing operation in the method of manufacturing the lightemitting device according to the first embodiment. FIG. 7A is aschematic cross-sectional view showing a light emitting element joiningoperation being a subordinate operation in the light emitting elementdisposing operation in the method of manufacturing the light emittingdevice according to the first embodiment. FIG. 7B is a schematiccross-sectional view showing a wiring operation being a subordinateoperation in the light emitting element disposing operation in themethod of manufacturing the light emitting device according to the firstembodiment. FIG. 7C is a schematic cross-sectional view showing asealing operation being a subordinate operation in the light emittingelement disposing operation in the method of manufacturing the lightemitting device according to the first embodiment.

Method of Manufacturing Light Emitting Device

The method of manufacturing the light emitting device 100 according tothe first embodiment includes a light emitting element preparingoperation S101, a package preparing operation S102, and a light emittingelement disposing operation S103.

The light emitting element preparing operation S101 is an operation ofpreparing a singulated light emitting element 1 of the configuration asshown in FIGS. 2A and 2B.

In the following, a description will be given of an exemplary operationof manufacturing the light emitting element 1 in a wafer-level process.However, an embodiment of the present invention is not limited thereto.Note that, in manufacturing the light emitting element 1 in awafer-level process, for example as shown in FIG. 6A, boundary lines BDbeing the virtual lines partitioning the individual light emittingelement 1 are defined, and a plurality of light emitting elements 1 ofan identical shape are formed.

Semiconductor Stacked-Layer Body Forming Operation

Specifically, firstly, on the substrate 11 of sapphire or the like,through MOCVD or the like, the n-type semiconductor layer 12 n, theactive layer 12 a and the p-type semiconductor layer 12 p aresuccessively stacked using the semiconductor materials noted above, toobtain the semiconductor stacked-layer body 12. Thereafter, the p-typesemiconductor layer 12 p is subjected to p-type annealing.

N-type Semiconductor Layer Exposing Operation

When the semiconductor stacked-layer body 12 is formed, at part of thesurface of the semiconductor stacked-layer body 12, from the uppersurface side, the entire p-type semiconductor layer 12 p and activelayer 12 a, and part of the n-type semiconductor layer 12 n are removedby etching. Thus, the step portion 12 b where the n-type semiconductorlayer 12 n is exposed at the bottom surface is formed.

Further, simultaneously, the region along the boundary lines BD isetched. Thus, the step portion 12 c is formed as the dicing street.

Light Transmissive Electrode Forming Operation

Thereafter, the light transmissive electrode 141 is formed throughsputtering or the like using a light transmissive and electricallyconductive material such as ITO, so as to cover substantially the entireupper surface of the p-type semiconductor layer 12 p.

P-side Pad Electrode Forming Operation

Further, the pad electrode 142 is formed through sputtering or the likeusing a metal material such as Cu or Au at part of the upper surface ofthe light transmissive electrode 141. Thus, the p-side electrode 14 isformed.

N-side Pad Electrode Forming Operation

Further, at the step portion 12 b, the pad electrode 132 is formedthrough sputtering or the like using a metal material such as Cu or Auat the upper surface of the n-type semiconductor layer 12 n. Thus, then-side electrode 13 is formed.

Note that, the order of forming the n-side electrode 13 and the p-sideelectrode 14 is not limited, and part of the subordinate operations, forexample, formation of the n-side electrode 13 and formation of thep-side pad electrode 142, may be simultaneously performed in anidentical subordinate operation.

Protective Film Forming Operation

Next, the protective film 15 covering the entire wafer is formed throughsputtering or the like using a light transmissive and electricallyinsulating material such as SiO₂, while forming the openings 15 n, 15 pat the external connection portions 13 a, 142 a respectively being theregions at the upper surfaces of the n-side electrode 13 and the padelectrode 142 for connecting to the outside.

Note that, the layers of the n-side electrode 13 and the p-sideelectrode 14 and the protective film 15 can be patterned by etching orlift-off using a mask which is formed into an appropriate shape byphotolithography.

By the foregoing subordinate operations, as shown in FIG. 6B, the lightemitting elements 1 in the wafer state can be formed.

Singulating Operation

Next, the light emitting elements 1 are singulated by cutting the waferalong the boundary lines BD. In this singulating operation, it ispreferable to use laser dicing capable of performing polygonal cut work,for singulating the light emitting elements 1 partitioned intonon-quadrangular shapes. By partitioning a plurality of light emittingelements 1 in a polygonal manner densely on the wafer, the number oflight emitting elements 1 that can be manufactured per wafer can furtherbe increased.

Note that, the boundary lines BD may be set such that the wafer can besingulated solely by a straight cutting work through dicing or scribingusing a dicing saw.

Further, the back side of the substrate 11 may be polished to reduce thethickness before the wafer is cut. This makes it easier to cut thewafer.

The laser dicing is a scheme of forming cut grooves by emitting laserlight (preferably, pulsed laser light of femtoseconds) so as toconcentrate inside the substrate 11, and changing the characteristic ofthe substrate 11 around the focused point. By emitting the laser lightto the substrate 11 along the boundary lines BD, polygonal cut groovescan be formed inside the substrate 11. Thereafter, by applying stress tothe substrate 11 using, for example, a roller, the wafer can besingulated from the cut grooves formed along the boundary lines BD.

Note that, since the scheme of cutting a wafer into non-quadrangularshape using laser dicing is detailed, for example, in JP 2006-135309 A,a further description will not be given.

The package preparing operation S102 is an operation of preparing thepackage 2 in the light emitting device 100 shown in FIGS. 1A to 1D. Thepackage 2 prepared in this operation is in the state where the lightemitting elements 1 are not mounted and the sealing resin 3 is notprovided.

In the package preparing operation S102, in order to prepare the package2, for example, the package 2 may be manufactured through any moldingmethod using a mold assembly such as transfer molding, compressionmolding, injection molding, extrusion molding and the like, or acommercially available package may be obtained.

Note that, the order of performing the light emitting element preparingoperation S101 and the package preparing operation S102 is notparticularly limited, and they may be performed in parallel.

A description will be given of an exemplary method of manufacturing thepackage 2. The package 2 can be manufactured by: interposing the leadframes (the lead electrodes 21, 22) formed by subjecting a sheet metalto punching work between upper and lower molds having a cavityconforming to the shape of the resin part 23; injecting a resin materialfrom a gate hole provided at part of the mold assembly; curing orhardening the resin material; and taking out the package 2 from the moldassembly. Further, in the case where a plurality of packages 2 beingconnected to each other by the lead frames is manufactured, the packages2 are singulated by cutting off the lead frames.

The light emitting element disposing operation S103 is an operation ofmounting the light emitting elements 1 prepared in the light emittingelement preparing operation S101 on the recess 23 a of the package 2prepared in the package preparing operation S102. More specifically, thelight emitting element disposing operation S103 includes, as thesubordinate operations, a light emitting element joining operation S201,a wiring operation S202, and a sealing operation S203.

Firstly, in the light emitting element joining operation S201, on theupper surfaces of the lead electrode 21 being the bottom surface 23 b ofthe recess 23 a of the package 2, the light emitting elements 1 arebonded using the die bonding resin 61 (preferably, silicone-base diebonding resin). At this time, through dispensing or pin transfer, thedie bonding resin 61 of a proper amount is supplied to the bonded siteson the upper surface of the lead electrode 21. Then, the light emittingelements 1 are transferred using a collet or the like to the bondedsites where the die bonding resin 61 is disposed, having the surfaceprovided with the n-side electrode 13 and the p-side electrode 14 facedup. The surfaces of the light emitting elements 1 on the substrate 11side and the upper surface of the lead electrode 21 are bonded, with thesides of the hexagons being the outer shape of the two light emittingelements 1 in a plan view at least partially opposing to each other notin parallel.

Further, in this step, the protective element 5 is bonded to the leadelectrode 22 using the electrically conductive joining member 62.

Next, in the wiring operation S202, the wires 4 are arranged among then-side electrode 13, the p-side electrode 14 and the lead electrodes 21,22 such that the two light emitting elements 1 are connected in seriesbetween the lead electrodes 21, 22. Further, the wire 4 is arranged suchthat the electrode provided on the upper surface side of the protectiveelement 5 and the lead electrode 21 are connected to each other. Thewires 4 can be arranged using a wire bonding apparatus.

Next, in the sealing operation S203, the sealing resin 3 in the liquidstate is packed in the recess 23 a of the package 2 through potting orthe like, and thereafter the sealing resin 3 is cured. Thus, the lightemitting elements 1 are sealed. The sealing resin 3 may be made of lighttransmissive resin containing particles of a fluorescent material (awavelength converting substance) or particles of a light diffusingsubstance.

Through the procedure described above, the light emitting device 100 canbe manufactured.

Variations

Next, with reference to FIGS. 8A to 10F, a description will be given oflight emitting devices according to Variations of the first embodiment.FIGS. 8A to 10F are each a schematic plan view showing the configurationof the light emitting device according to Variation of the firstembodiment.

Note that, FIGS. 8A to 10F show the configuration of light emittingdevices 100C to 100P in a simplified manner. That is, in connection withthe package 2, only the recess 23 a being the region for mounting thelight emitting elements 1 and of which opening and bottom surface areeach square in a plan view is shown. In connection with the lightemitting elements, only the outer shape in a plan view is shown.Further, other members such as the protective element and the wires areomitted.

Further, the reference character subscripts “P, Q, R, S” relating to thelight emitting elements 1 are provided for identifying the lightemitting elements 1, and light emitting elements 1 _(P), 1 _(Q), 1 _(R),1 _(S) is have the same configuration as the light emitting element 1shown in FIGS. 2A and 2B. The same holds true for the referencecharacter subscripts “P, Q, R, S” relating to the light emittingelements 1A, 1B, 1C.

In the light emitting device 100C, two light emitting elements 1 _(P), 1_(Q) each having an outer shape of an approximately regular hexagon arealigned in the lateral direction. In a plan view, one side of one lightemitting element 1 _(Q) and an angle (vertex) of other light emittingelement 1 _(P) oppose to each other. Therefore, between the lightemitting element 1 _(P) and the light emitting element 1 _(Q), nolateral side surfaces oppose to each other in parallel.

In the light emitting device 100D, the light emitting element 1 havingan outer shape of an approximately regular hexagon and the lightemitting element 1A having an outer shape of an approximately regularpentagon are aligned in the lateral direction. In this manner, thepolygons differing in the number of corners may be disposed incombination.

In the light emitting devices 100E to 100H, four light emitting elements1 _(P), 1 _(Q), 1 _(R), 1 _(S) each having an outer shape of anapproximately regular hexagon are square arrayed two dimensionally.

In the light emitting device 100E, a pair of the light emitting element1 _(P) and the light emitting element 1 _(Q) adjacent to each other inthe lateral direction and a pair of the light emitting element 1 _(R)and light emitting element 1 _(S) adjacent to each other in the lateraldirection are disposed such that respective one sides of theapproximately regular hexagons in each pair in a plan view are inparallel to each other. In this case also, other two sides of theapproximately regular hexagons in each pair opposing in the lateraldirection do not oppose to the counterpart two sides in parallel.Further, in connection with a pair of the light emitting element 1 _(P)and the light emitting element 1 _(R) adjacent to each other in thelongitudinal direction and a pair of the light emitting element 1 _(Q)and the light emitting element 1 _(S) adjacent to each other in thelongitudinal direction, corners oppose to the counterpart and none ofthe sides oppose to the counterpart in parallel between the pairs in aplan view.

In this manner, in the case where all the plurality of light emittingelements 1 are square arrayed two dimensionally in the same orientation,at least part of the sides can be avoided from opposing to each other inparallel.

In the light emitting device 100F, the light emitting elements 1adjacent to each other in the longitudinal and lateral directions arerotated by 30° (or 30°+60°×N (N is an integer)) relative to each otherabout an axis perpendicular to the upper surface. That is, the lightemitting elements 1 adjacent to each other in the longitudinal andlateral directions oppose to each other such that one side of one lightemitting element 1 and one corner of other light emitting element 1oppose to each other in a plan view. Therefore, the light emittingelements 1 adjacent to each other in the longitudinal direction or inthe lateral direction are disposed such that their respective sides donot oppose to each other in parallel in a plan view.

In the light emitting device 100G, the light emitting elements 1adjacent to each other in the lateral direction are disposed as beingoriented in the same direction, and the light emitting elements 1adjacent to each other in the longitudinal direction are rotated by 30°(or 30°+60°×N (N is an integer)) relative to each other about an axisperpendicular to the upper surface. In more detail, the light emittingelement 1 _(P) and the light emitting element 1 _(Q) are disposed suchthat their respective one corners oppose to each other in the lateraldirection, and the light emitting element 1 _(R) and the light emittingelement 1 _(S) are disposed such that their respective one sides opposeto each other in parallel in the lateral direction. Therefore, inconnection with the light emitting elements 1 adjacent to each other inthe longitudinal direction, one side of one light emitting element 1 andone corner of other light emitting element 1 oppose to each other.

In the light emitting device 100H, three light emitting elements 1 _(P),1 _(R), 1 _(S) is are arranged orienting in the same direction, and thelight emitting element 1 _(Q) is rotated by 30° (or 30°+60°×N (N is aninteger)) relative to other light emitting element 1 _(P) and othersabout an axis perpendicular to the upper surface. Therefore, between thelight emitting element 1 _(R) and the light emitting element 1 _(S),their respective one sides oppose to each other in parallel, whereasbetween the light emitting element 1 _(P) and the light emitting element1 _(Q), one side of the light emitting element 1 _(P) and one corner ofthe light emitting element 1 _(Q) oppose to each other and theirrespective sides do not oppose to each other. In this manner, by simplychanging the orientation of one of a plurality of light emittingelements 1, the number of mutually facing lateral sides of adjacent onesof light emitting elements that are in parallel to each other in a planview can be reduced.

In the light emitting devices 100I, 100J, four light emitting elements 1are all oriented in the same direction, and disposed in a zigzag mannertwo dimensionally.

In the light emitting device 100I, the light emitting elements 1 _(P), 1_(S) arranged in odd rows (the first and third rows) are disposed closeto each other, and such that their respective one sides oppose to eachother. Further, the light emitting elements 1 _(Q), 1 _(R) arranged inan even row (the second row) are disposed spaced apart from each otherhaving the light emitting elements 1 _(P), 1 _(S) in the upper and lowerrows interposed therebetween, and such that their respective one cornersoppose to each other.

Further, as compared to the square array, since the four light emittingelements 1 are densely disposed in one direction (the longitudinaldirection), a greater number of light emitting elements 1 can bearranged in a certain area.

Here, in connection with the light emitting elements 1 adjacent to eachother in a diagonal direction, for example the light emitting element 1_(P) and the light emitting element 1 _(Q), part of their respective onesides oppose to each other in parallel. Further, while the lightemitting elements 1 _(P), 1 _(S) adjacent to each other in thelongitudinal direction have their respective one sides opposed to eachother in parallel, they are spaced apart as compared to the case whenbeing square arrayed. Accordingly, the length of the sides opposing toeach other in parallel can be shortened than in the case where the lightemitting elements having an outer shape of a square are square arrayedin the same direction. Hence, the amount of light exchanged between thelateral side surfaces of the light emitting elements 1 can be reduced.

In the light emitting device 100J, the light emitting elements 1 _(P), 1_(S) arranged in odd rows (the first and third rows) are disposed closeto each other, and such that their respective one corners oppose to eachother in the longitudinal direction. Further, the light emittingelements 1 _(Q), 1 _(R) in an even row (the second row) are disposedspaced apart from each other having the light emitting elements 1 _(P),1 _(S) in the upper and lower rows interposed therebetween, and suchthat their respective one sides oppose to each other in parallel. Whilethe light emitting elements 1 _(Q), 1 _(R) have their respective onesides opposed to each other in parallel, they are spaced apart. Hence,the amount of light exchanged between the lateral side surfaces of thelight emitting elements 1 _(Q), 1 _(R) can be reduced. Further, in thelight emitting device 100J, similarly to the light emitting device 100I,the four light emitting elements 1 are densely arranged in one direction(the longitudinal direction). Further, in the light emitting device100J, since the light emitting elements 1 are disposed such that thesmallest width direction of each light emitting element 1 in a plan view(the direction perpendicular to one side of the hexagon) agrees with theabove-described densely arranged direction, the light emitting element 1can be more densely arranged.

In light emitting devices 100K to 100N, four light emitting elements 1Beach having an outer shape of an approximately regular octagon arearranged.

In the light emitting device 100K, the four light emitting elements 1Bare all square arrayed two dimensionally as being oriented in the samedirection. In a plan view, respective one side of the approximatelyregular octagons being the outer shape of the light emitting elements 1Badjacent to each other in the longitudinal and lateral directions areopposed to each other in parallel. Therefore, in the light emittingdevice 100K, other two sides opposing to each other between the adjacentlight emitting elements 1 do not oppose to each other in parallel.

In the light emitting device 100L, the four light emitting elements 1Bare all square arrayed two dimensionally as being oriented in the samedirection. The light emitting elements 1B are rotated by 22.5° (or22.5°+45°×N (N is an integer)) about an axis perpendicular to the uppersurface. Therefore, in the light emitting device 100L, while all thelight emitting elements 1B are oriented in the same direction, in a planview, their respective corners oppose to each other and their respectivesides do not oppose to each other in parallel.

In the light emitting device 100M, the four light emitting elements 1Bare square arrayed two dimensionally, and the light emitting elements 1Badjacent to each other in the longitudinal and lateral directions arerotated by 22.5° (or 22.5°+45°×N (N is an integer)) relative to eachother about an axis perpendicular to the upper surface. Therefore, thelight emitting elements 1B adjacent to each other in the longitudinaland lateral directions have none of their respective sides opposed toeach other in parallel.

In the light emitting device 100N, the four light emitting elements 1Bare all disposed in a staggered arrangement two dimensionally as beingoriented in the same direction. The light emitting elements 1B arerotated such that their respective sides are inclined by 22.5° relativeto the longitudinal direction or the lateral direction. Further, thelight emitting elements 1B_(P), 1B_(S) in an even column (the secondcolumn) are disposed as being spaced apart from each other, having thelight emitting elements 1B_(Q), 1B_(R) arranged in the right and leftcolumns interposed therebetween, and such that respective one corners ofthe light emitting elements 1B_(P), 1B_(S) oppose to each other in closeproximity. The light emitting elements 1B adjacent to each other in adiagonal direction (for example, a pair of the light emitting element1B_(P) and the light emitting element 1B_(Q)) have only part of theirrespective one sides oppose to each other in parallel, and other sidesdo not oppose to each other in parallel. Further, as compared to thesquare array arrangement, since the four light emitting elements 1B aredensely disposed in one direction (the lateral direction), a greaternumber of light emitting elements 1 can be disposed in a certain area.

In the light emitting device 1000, four light emitting elements 1A eachhaving an outer shape of an approximately regular pentagon are squarearrayed all being oriented in the same direction. Further, in the lightemitting device 100P, four light emitting elements 1C each having anouter shape of an approximately regular heptagon are square arrayed allbeing oriented in the same direction.

As in the case of the light emitting devices 1000, 100P, when there areno combinations of sides of light emitting elements being parallel toeach other, even when the light emitting elements are square arrayed allbeing oriented in the same direction, the adjacent light emittingelements 1A, 1C have none of their respective sides paralleled to eachother.

Note that, the outer shape of each light emitting element mounted in thelight emitting device is not limited to an approximately regularpolygon, and just required to be a convex polygon having five or morecorners and in which every interior angle is less than 180°. Further, asthe outer shape of the light emitting element approximates a circle, thelight extracted from the side surfaces of each light emitting elementreduces. Therefore, the outer shape is preferably a polygon having eightor less corners.

Further, the number of light emitting elements mounted on the lightemitting device is not limited to two or four, and may be three or fiveor more. Still further, the region where the light emitting elements aremounted is not limited to a square or an approximately square region,and may be set to be rectangular, circular, or polygonal as appropriate.

Second Embodiment

Next, with reference to FIGS. 11A and 11B, a description will be givenof a light emitting device according to a second embodiment.

FIG. 11A is a schematic plan view showing the configuration of the lightemitting device according to the second embodiment. FIG. 11B is aschematic plan view showing the configuration of a light emittingelement in the light emitting device according to the second embodiment.

Note that, similarly to FIGS. 8A to 10F, FIG. 11A shows theconfiguration of the light emitting device in a simplified manner.Further, in FIG. 11B, the configuration of the light emitting elementshows the outer shape in a plan view and respective external connectionportions of the n-side electrode 13 and the p-side electrode 14. Stillfurther, the vertexes of the hexagon that is the outer shape of thelight emitting element is indicated by A to F for the sake ofconvenience. The same holds true for FIGS. 12A and 12B referred tolater.

Configuration of Light Emitting Device

In a light emitting device 200 according to the second embodiment, onthe bottom surface 23 b of the recess 23 a of the package 2, four lightemitting elements 1D (1D_(P), 1D_(Q), 1D_(R), 1D_(S)) each having anouter shape of an elongated hexagon in a plan view are arrangedtwo-dimensionally, about an approximately quadrangular (approximatelysquare) gap 201.

Note that, the package 2 is similar to that in the first embodiment.Further, the light emitting element 1D has a similar configuration asthat of the light emitting element 1 according to the first embodiment,except for the outer shape in a plan view. Accordingly, the detaileddescription on the configuration and the method of manufacturing will beomitted.

The interior angles of vertexes A, D of the elongated hexagon of theouter shape of the light emitting element 1D are a same angle of equalto or less than 90°, and 90° is preferable. Further, the interior anglesof other vertexes B, C, E, F are a same angle of equal to or greaterthan 135°, and 135° is preferable. Still further, the light emittingelement 1D has an elongated outer shape in a plan view, in which adiagonal line AD is in the long-length direction, and the directionnormal from a point on a side CB to a side EF is the short-lengthdirection. Sides AB, CD, DE, FA have a same length. Further, the sidesBC and EF have a same length that is preferably longer than the othersides. Still further, preferably, respective external connectionportions of the n-side electrode 13 and the p-side electrode 14 arerespectively provided near one end and other end in the long-lengthdirection.

In the present embodiment, a description will be given of the case wherethe interior angle of each of the vertexes A, D is 90°, the interiorangle of each of the vertexes B, C, E, and F is 135°, and the sides BCand EF are identical to diagonal lines BF and CE in length. Accordingly,the sides BC and EF are the long sides longer than the other sides, andthe other sides are the short sides.

In connection with the light emitting device 200, the bottom surface 23b of the recess 23 a being approximately square in a plan view is theregion for disposing the light emitting elements 1D, and the center ofthe disposition region in a plan view is 0. The four light emittingelements 1D are disposed having respective one long sides orientedtoward the center O. Therefore, the four light emitting elements 1D aredisposed so as to form the approximately square gap 201 at the center Oabout which the light emitting elements 1D are disposed.

Note that, the center of the four light emitting elements 1D notnecessarily agree with the center O of the disposition region, and thecenter may be at different position than the center O.

Further, it can be regarded that the four light emitting elements 1D aredisposed in a staggered arrangement two dimensionally. The lightemitting elements 1D_(P), 1D_(S) in odd rows (the first and third rows)are disposed such that the long-length direction becomes parallel to thelateral direction in a plan view, and the light emitting elements1D_(Q), 1D_(R) in an even row (the second row) are disposed such thatthe long-length direction becomes parallel to the longitudinal directionin a plan view. In other words, the light emitting elements 1D_(P),1D_(S) in the odd rows and the light emitting elements 1D_(Q), 1D_(R) inthe even row are rotated by 90° relative to each other about an axisperpendicular to the upper surface.

The four light emitting elements 1D are disposed such that theirrespective short sides of the elongated hexagons being the outer shapein a plan view oppose to each other in parallel. Further, though theirrespective long sides of the elongated hexagons oppose to each other inparallel, they oppose to each other relatively spaced apart via the gap201. Accordingly, a great amount of light is input from the lateral sidesurfaces of the light emitting elements 1D at only two short sides perlight emitting element 1D.

Therefore, even when a plurality of light emitting elements 1D aredensely disposed in close proximity to each other, the amount of lightinput from the lateral side surfaces of the light emitting elements 1Dis limited. Hence, the light extraction efficiency can be improved.

Note that, the light emitting device 200 is different from the lightemitting device 100 according to the first embodiment in just the outershape of the light emitting elements, the number of disposed lightemitting elements and the disposition position of the light emittingelements. Therefore, the detailed description of the manufacturingmethod will be omitted.

Simulation of Luminous Flux of Light Emitting Device

Next, with reference to FIGS. 12A to 13, a description will be given ofthe simulation of the luminous flux of the output light obtained whenthe distance between respective short sides of the light emittingelements 1D opposing to each other in parallel in the light emittingdevice 200 is varied.

FIG. 12A is a schematic plan view for describing the disposition oflight emitting elements used in simulating the luminous flux of thelight emitting device according to the second embodiment. FIG. 12B is aschematic plan view for describing disposition of light emittingelements used in simulating the luminous flux of a light emitting deviceaccording to Comparative Example. FIG. 13 is a graph showing thesimulation results of the luminous flux of the light emitting deviceaccording to the second embodiment and the light emitting deviceaccording to comparative example.

Simulation Condition

A description will be given of the shape of the model of the lightemitting device 200 used in simulating the luminous flux.

The light emitting element 1D has an outer shape of an elongated hexagonin a plan view shown in FIG. 11B. The interior angles of vertexes A, Dare each 90°, and the interior angles of the vertexes B, C, E, F areeach 135°. The sides BC and EF being the long sides each have a lengthof 500 μm; the distance between the sides BC and EF is 500 μm; and thelight emitting elements 1D each have a thickness of 150 μm. Accordingly,the outer-shape area of the light emitting element 1D in a plan view is375000 μm². Further, the light emission area obtained by subtracting thearea of the step portion from which the p-type semiconductor layer 12 pand the active layer 12 a are removed for providing the n-side electrode13 is 345450 μm².

The recess 23 a of the package 2 is opened in a square shape of whichone side has a length of 2600 μm. The bottom surface 23 b of the recess23 a forms a square of which one side has a length of 2240 μm.Accordingly, the lateral side surfaces of the recess 23 a are linearlyinclined widening upward in a cross-sectional view.

As Comparative Example, the luminous flux was simulated also with alight emitting device 1200 in which light emitting elements 1001 havingthe outer-shape area, the light emission area and the thicknessidentical to those of the light emitting element 1D, and each having asquare outer shape were mounted. Note that, the approximately squareouter shape of each light emitting element 1001 has a side of 612.38 μm.

Further, in connection with the light emitting device 200, the fourlight emitting elements 1D are disposed such that respective short sidesof the elongated hexagons being the outer shape in a plan view oppose toeach other in parallel, and such that the center of the four lightemitting elements 1D agrees with the center O of the bottom surface 23 bof the recess 23 a. Further, the light emitting elements 1D_(P), 1D_(S)are disposed such that the long sides of the outer shape become parallelto one side of the square being the shape of the bottom surface 23 b,and the light emitting elements 1D_(Q), 1D_(R) are disposed such thatthe long sides of the outer shape become perpendicular to the long sidesof the outer shape of the light emitting elements 1D_(P), 1D_(S.)

Still further, the luminous flux was simulated while gradually varyingthe distance between respective short sides of the light emittingelements 1D opposing to each other in parallel from the state where thelight emitting elements 1D are substantially closely attached to eachother (the state indicated as “dense” in FIG. 12A) to the state wherethe outer long sides are substantially in contact with the sides of thebottom surface 23 b (the state indicated as “sparse” in FIG. 12A).

Note that, the distance between the short sides is 7.05 μm in the“dense” state, and 493.5 μm in the “sparse” state.

Further, in connection with the light emitting device 1200 ofComparative Example, the four light emitting elements 1001 are squarearrayed in two rows and two columns. At this time, the four lightemitting elements 1001 are disposed such that their center agrees withthe center O of the bottom surface of the recess 23 a. Further, the fourlight emitting elements 1001 are arranged such that the squares beingthe outer shape of the light emitting elements 1001 are orientedsimilarly to the square being the shape of the bottom surface 23 b.Accordingly, the light emitting elements 1001 are disposed such thatrespective one sides of the squares being the outer shape of the lightemitting elements 1001 being adjacent to each other in the longitudinaland lateral directions in a plan view oppose to each other in parallel.

Further, the luminous flux was simulated while gradually varying thedistance between respective sides of the squares of the light emittingelements 1001 opposing to each other in parallel from the state wherethe light emitting element 1001 are substantially closely attached toeach other (the state indicated by “dense” in FIG. 12B) to the statewhere the outer long sides are substantially in contact with the sidesof the bottom surface 23 b (the state indicated as “sparse” in FIG.12B).

Note that, the distance between the sides opposing in parallel is 7.62μm in the “dense” state, and 987.62 μm in the “sparse” state.

Simulation Result

For reference, simulation was conducted as to the luminous flux of alight emitting device in which one light emitting element 1D or onelight emitting element 1001 is mounted substantially at the center ofthe bottom surface 23 b of the package 2. As a result, when the luminousflux of the light emitting device in which one light emitting element1001 having a square outer shape was mounted was 100%, the luminous fluxof the light emitting device in which one light emitting element 1Dhaving an elongated hexagonal outer shape was mounted was 99.6%. It wasfound that, in the cases where one light emitting element was mounted,though the luminous flux was slightly greater with the light emittingelement having a square outer shape, they were substantially the same.

Further, FIG. 13 shows the simulation results as to the cases where thefour light emitting elements were mounted and the interval between thelight emitting elements were varied. In FIG. 13, the vertical axisrepresents the luminous flux proportion of the light emitting device 200(plotted by filled circles) and the light emitting device 1200 (plottedby filled squares) where the luminous flux of light emitting devices ineach of which one light emitting element of the corresponding outershape is mounted is 100%. Further, the inter-chip distance on thehorizontal axis represents the distance between respective sides of thelight emitting elements opposing to each other in parallel. On thehorizontal axis, the “dense” state is “0” and the “sparse” state is “1”.

In both the light emitting device 200 and the light emitting device1200, as the inter-chip distance becomes greater, the luminous fluxproportion increases. On the other hand, the light emitting device 200is greater than in the luminous flux proportion than the light emittingdevice 1200 at every inter-chip distance. In particular, when the lightemitting elements are disposed in the “dense” state, the light emittingdevice 200 prominently shows the higher values.

In the light emitting device 1200, two sides of a square being the outershape of one light emitting element 1001 oppose in parallel to otheradjacent light emitting elements 1001. On the other hand, in the lightemitting device 200, only two short sides of a hexagon being the outershape of one light emitting element 1D oppose in parallel in closeproximity to other light emitting elements 1D. Though one long side ofone light emitting element 1D oppose in parallel to one long side ofother light emitting element 1D, these long sides are spaced apart fromeach other at least by the length of themselves. Therefore, the amountof light entering from the side surfaces corresponding to the long sidesreduces. Accordingly, as the inter-chip distance is smaller, that is,when the light emitting elements are disposed denser, the luminous fluxextracted to the outside becomes greater with the light emitting device200 than with the light emitting device 1200.

Further, with the light emitting device 1200, when the inter-chipdistance is “sparse”, the luminous flux proportion slightly reduces.This is because that, when the light emitting elements 1001 each havinga square outer shape are disposed excessively near to the lateral sidesurfaces of the recess 23 a of the package 2, a greater amount of lightreflected from the lateral side surfaces of the recess 23 a enters fromthe lateral side surfaces of the light emitting element 1001. With thelight emitting device 200, even when the light emitting elements 1D aredisposed in close proximity to the lateral side surfaces of the recess23 a, only one long side of a hexagon being the outer shape in a planview oppose in parallel to one side of a square corresponding to thelateral side surfaces of the recess 23 a, and the short sides do notoppose in parallel to the sides of the square. Therefore, the amount oflight reflected from the lateral side surfaces of the recess 23 a andenters from the side surfaces of the light emitting elements 1D reduces.Accordingly, even when the light emitting elements 1D are disposed soclose to the lateral side surfaces of the recess 23 a that they arebrought into contact, the luminous flux from the light emitting device200 does not reduce.

Therefore, it can be seen that, with the light emitting device 200, ahigher luminous flux proportion can be obtained even when the lightemitting elements are arranged in close proximity to the lateral sidesurfaces of the recess 23 a. In other words, even when the area of thebottom surface 23 b of the recess 23 a being the region where the lightemitting elements 1D are mounted is reduced, the luminous flux of thelight emitting device 200 does not reduce.

Accordingly, the disposition where the light emitting elements 1D havinga hexagonal outer shape are disposed having their respective short sidesopposed to each other in parallel having the approximately square gap201 interposed therebetween at the center is the configuration suitablefor miniaturizing the package 2, or increasing the output by mounting aplurality of light emitting elements 1D.

Third Embodiment

Next, with reference to FIG. 14, a description will be given of a lightemitting device according to a third embodiment. FIG. 14 is a schematicplan view showing the configuration of the light emitting deviceaccording to the third embodiment.

Note that, since the light emitting element 1D and the package 2 aresimilar to those in the second embodiment, the detailed description ofthe configuration of each member will be omitted.

In a light emitting device 300 according to the third embodiment, on thebottom surface 23 b of the recess 23 a of the package 2, four lightemitting elements 1D (1D_(P), 1D_(Q), 1D_(R), 1D_(S)) each having anelongated hexagonal outer shape in a plan view are disposed in a crossshape.

More specifically, in the light emitting device 300, the four lightemitting elements 1D are disposed each having one of the vertexes formedbetween short sides and of which interior angle is 90° oriented towardthe center O. Further, the four light emitting elements 1D are disposedsuch that the long-length direction of two light emitting elements1D_(P), 1D_(S) becomes parallel to the longitudinal direction and thelong-length direction of the other two light emitting elements 1D_(Q),1D_(R) becomes parallel to the lateral direction.

Note that, the center position to which the vertexes of the four lightemitting elements 1D are oriented does not necessarily agree with thecenter O of the disposition region, and may be displaced from the centerO.

Here, the light emitting elements 1D are disposed such that the twoshort sides forming the 90° interior angle of one light emitting element1D oppose in parallel to the two short sides forming the 90° interiorangle of other light emitting element 1D in a plan view. Further, twolong sides of one light emitting element 1D do not oppose to any sidesof other light emitting elements 1D in a plan view. Further, though thelong sides oppose in parallel to the sides of the square being the shapeof the recess 23 a, they are spaced apart from the sides of the squareby at least 1.5 times as long as the length of the long sides. Further,in a plan view, other short sides of one light emitting element 1D donot oppose in parallel to any sides of other light emitting elements 1D,or to the sides of the square being the shape of the recess 23 a.Accordingly, since the amount of the output light from the side surfacesof the light emitting element 1D and the reflection light from thelateral side surfaces of the recess 23 a entering from the side surfacesof the light emitting element 1D reduces, the output of the lightemitting device 300 can be increased.

Further, it can be regarded that the four light emitting elements 1D aredisposed in a staggered arrangement two dimensionally. The lightemitting element 1D_(P), 1D_(S) in odd rows (the first and third rows)are disposed such that the long-length direction becomes parallel to thelongitudinal direction in a plan view, and the light emitting elements1D_(Q), 1D_(R) in an even row (the second row) is disposed such that thelong-length direction becomes parallel to the lateral direction in aplan view. In other words, the light emitting elements 1D_(P), 1D_(S) inthe odd rows and the light emitting elements 1D_(Q), 1D_(R) in the evenrow are rotated by 90° relative to each other about an axisperpendicular to the upper surface.

Note that, the interior angle and the length of the side of the lightemitting element 1D can be determined similarly to the light emittingelement 1D according to the second embodiment. Accordingly, eachinterior angle formed between short sides is preferably 90°, but may be90° or less. Other interior angles may each preferably be 135°, but maybe 135° or more.

Further, since the light emitting device 300 is different from the lightemitting device 200 according to the second embodiment only in theorientation of the light emitting elements 1D. Therefore, the detaileddescription as to the manufacturing method will be omitted.

In the foregoing, while the light emitting device according to theembodiments of the present invention has been specifically describedbased on the embodiments, the spirit of the present invention is notlimited by such description, and should be construed broadly based onthe scope of claims. Further, it goes without saying that variouschanges and modifications based on such description are also included inthe spirit of the present invention.

The light emitting device according to the embodiments of the presentdisclosure can be used for various light sources, such as a backlightlight source of a liquid crystal display, various illumination devices,a large-size display, various display apparatuses such as anadvertisement or a destination guide, and furthermore, an image readingapparatus in a digital video camera, a facsimile, a copier, a scannerand the like, and a projector apparatus.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A light emitting device comprising: a packagehaving an upper surface and a direction substantially perpendicular tothe upper surface; and a plurality of light emitting elements disposedon the upper surface, each of the plurality of light emitting elementshaving a polygonal shape with five or more corners viewed in thedirection, an interior angle at each of the corners being less than180°, the plurality of light emitting elements comprising: a first lightemitting element having a first bottom surface, a first top surfaceopposite to the first bottom surface in the direction, and a firstlateral side surface between the first bottom surface and the first topsurface, the first light emitting element being disposed on the uppersurface of the package at the first bottom surface; and a second lightemitting element having a second bottom surface, a second top surfaceopposite to the second bottom surface in the direction, and a secondlateral side surface between the second bottom surface and the secondtop surface, the second light emitting element being disposed on theupper surface of the package at the second bottom surface, the secondlateral side surface being provided not to oppose to the first lateralside surface in substantially parallel.
 2. The light emitting deviceaccording to claim 1, wherein the polygon has eight or less corners. 3.The light emitting device according to claim 1, wherein the polygon is ahexagon, the plurality of light emitting elements are disposed in aplurality of rows viewed in the direction, and the light emittingelements disposed in an even row are rotated by 90° about an axisperpendicular to the upper surface of the package relative to the lightemitting elements arranged in an odd row.
 4. A light emitting devicecomprising: a package having a recess with a bottom surface and adirection substantially perpendicular to the bottom surface; and aplurality of light emitting elements disposed on the bottom surface,each of the plurality of light emitting elements having a polygonalshape with five or more corners viewed in the direction, an interiorangle at each of the corners being less than 180°.
 5. The light emittingdevice according to claim 4, wherein the polygon is a hexagon, and outof three pairs of the interior angles opposing to each other diagonally,two pairs of the interior angles have an identical angle equal to orgreater than 135°, and one pair of the interior angles have an identicalangle equal to or smaller than 90°.
 6. The light emitting deviceaccording to claim 4, wherein the plurality of light emitting elementsare disposed in a staggered arrangement in a plurality of rows viewed inthe direction, and the light emitting elements disposed in an even roware rotated by 90° about an axis perpendicular to the plane relative tothe light emitting elements disposed in an odd row.
 7. The lightemitting device according to claim 6, wherein, in the hexagon, the onepair of the interior angles are each 90°, and the two pairs of interiorangles are each 135°.
 8. The light emitting device according to claim 7,wherein in the hexagon, four sides forming the one pair of interiorangles are shorter than other two sides, and the plurality of lightemitting elements are disposed such that, between adjacent ones out ofthe plurality of light emitting elements, their respective side surfacesbeing the other two sides do not oppose to each other in parallel. 9.The light emitting device according to claim 4, wherein the plurality oflight emitting elements are disposed such that, between adjacent onesout of the plurality of light emitting elements, their respective sidesurfaces oppose to each other substantially in parallel.
 10. The lightemitting device according to claim 9, wherein the light emittingelements are at least four in number, and the four light emittingelements out of the plurality of light emitting elements are disposed soas to form an approximately quadrangular gap at a center viewed in thedirection.
 11. The light emitting device according to claim 9, whereinthe light emitting element are at least four in number, and four lightemitting elements out of the plurality of light emitting elements aredisposed in a cross shape viewed in the direction with a gap from eachother.
 12. The light emitting device according to claim 1, wherein, eachof the light emitting elements includes a pair of electrodes forconnecting to an outside, one electrode of the pair being disposed nearone end of a longest diagonal line viewed in the direction, and otherelectrode of the pair being disposed near other end of the longestdiagonal line viewed in the direction.
 13. The light emitting deviceaccording to claim 1, wherein the light emitting elements are bonded tothe package using silicone-base die bonding resin.
 14. The lightemitting device according to claim 13, further comprising a sealingresin sealing the light emitting elements, wherein an index ofrefraction of the die bonding resin is equal to or smaller than an indexof refraction of the sealing resin.
 15. A light emitting devicecomprising: a package having an upper surface and a directionsubstantially perpendicular to the upper surface; and a plurality oflight emitting elements disposed on the upper surface, each of theplurality of light emitting elements having a polygonal shape with fiveor more corners viewed in the direction, an interior angle at each ofthe corners being less than 180°, the plurality of light emittingelements comprising: a first light emitting element and a second lightemitting element which are provided such that one corner of the firstlight emitting element is closest to the second light emitting element.